This invention relates to a process for the liquefaction of solid carbonaceous materials by hydrogenolysis. More specifically it relates to the electro-deposition of metals onto coal particles, the use of the deposited metals as catalysts for hydrogenolysis of such coal and the recovery of the metal catalysts after hydrogenolysis.
Hydrogenolysis is a well known and widely practiced method of converting solid hydrocarbonaceous material such as coal into liquid fuels. Early in the development of this process it was discovered that process time could be reduced by conducting the hydrogenolysis at elevated temperatures and pressures. Later is was discovered and it is now widely known that the presence of certain metals or metal alloys increase the efficiency of the hydrogenolysis process even at mild reaction conditions.
In a typical hydrogenolysis step, the solid carbonaceous material is slurried in a heavy oil, which may be a recycled portion of the oil which is a product of the hydrogenolysis process. The slurry is retained in the pressure vessel and held at an elevated temperature and pressure while hydrogen gas is circulated through the slurry.
Although hydrogenolysis processes for the liquefaction of coal have undergone a great deal of study and improvement, hydrogenolysis has yet to be incorporated as a step in large scale coal liquefaction facilities because of the high operating costs and the large capital investment required. The present invention increases the efficiency and consequently the attractiveness of the hydrogenolysis process. This increased efficiency is attained by bringing the catalyst metal into closer contact with the coal product than has previously been possible, thereby maximizing the catalytic effect. The present invention further includes a method for an efficient recovery of the metal catalyst so that it may be continuously recycled in the system.
U.S Pat. No. 1,299,565 and more recently, U.S Pat. No. 3,703,446 describe the electroplating of metals onto particles of carbon. The electroplated graphite serves as a catalyst for hydrogenation processes such as the saturation of fatty oils. These patents do not deal with the problem of bringing metal catalysts into close contact with solid reactants. They show only the plating of purified carbon and are not concerned with electroplating catalyst metal directly upon naturally occurring hydrocarbonaceous materials, the very material which is hydrogenolyzed in the process. The plated carbon in these references was itself inert and served only as a carrier for the catalyst metals.
Electrolytic recovery of metals from metal ores and especially from graphite bodies has appeared in a variety of forms in the prior art.